<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>栅格系统</title>
    <!-- 引入Bootstrap的css样式 -->
    <link rel="stylesheet" href="css/bootstrap.min.css" />
    <style>
        body {
            margin-top: 30px;

        }

        .container {
            outline: 1px solid black;
        }

        .col-md-1 {
            outline: 1px solid black;
        }
        .col-md-4 {
            outline: 1px solid black;
        }
        .col-md-6 {
            outline: 1px solid black;
        }
        .col-md-8 {
            outline: 1px solid black;
        }
        .col-md-12 {
            outline: 1px solid black;
        }
    </style>
    <!-- 引入jQuery -->
    <script type="text/javascript" src="js/jquery-3.3.1.min.js"></script>
    <script type="text/javascript" src="js/bootstrap.min.js"></script>
</head>

<body>
    <!-- 栅格系统最外层的容器必须是container -->
    <div class="container">
        <!-- 栅格系统的每一行都是row -->
        <div class="row">
            <!-- 栅格系统的每一列，使用中屏，宽度为1/12 -->
            <div class="col-md-1">第一列</div>
            <div class="col-md-1">第二列</div>
            <div class="col-md-1">第三列</div>
            <div class="col-md-1">第四列</div>
            <div class="col-md-1">第五列</div>
            <div class="col-md-1">第六列</div>
            <div class="col-md-1">第七列</div>
            <div class="col-md-1">第八列</div>
            <div class="col-md-1">第九列</div>
            <div class="col-md-1">第十列</div>
            <div class="col-md-1">第十一列</div>
            <div class="col-md-1">第十二列</div>
        </div>
        <div class="row">
            <!-- 栅格系统的每一列，使用中屏，宽度为4/12 -->
          <div class="col-md-4">1</div>
          <div class="col-md-4">2</div>
          <div class="col-md-4">3</div>
        </div>
        <div class="row">
            <!-- 栅格系统的每一列，使用中屏，宽度为6/12 -->
          <div class="col-md-6">1</div>
          <div class="col-md-6">2</div>
        </div>
        <div class="row">
            <!-- 栅格系统的每一列，使用中屏，宽度为8 4 -->
          <div class="col-md-8">1</div>
          <div class="col-md-4">2</div>
        </div>
        <div class="row">
            <!-- 栅格系统的每一列，使用中屏，footer -->
            <div class="col-md-12">footer</div>
        </div>
    </div>
</body>

</html>